Spin susceptibility in a narrow degenerate band
نویسندگان
چکیده
It has been shown that the static spin susceptibility of the Hubbard model of correlations for a narrow band calculated in the CPA remains finite for any simple-band model and the carrier number, except possibly in the case of a precisely half filled band. We show that this statement is more general and should be true if the Hubbard model could be solved exactly within the alloy analogy approximation. We then consider a model with orbital degeneracy and show that in this case there can be an instability in the susceptibility and we correlate this instability with Hund’s rule.
منابع مشابه
Efficient Spin Injection into Silicon and the Role of the Schottky Barrier
Implementing spin functionalities in Si, and understanding the fundamental processes of spin injection and detection, are the main challenges in spintronics. Here we demonstrate large spin polarizations at room temperature, 34% in n-type and 10% in p-type degenerate Si bands, using a narrow Schottky and a SiO2 tunnel barrier in a direct tunneling regime. Furthermore, by increasing the width of ...
متن کاملBiCu 2 VO 6 : a new narrow - band spin - gap material
– A new spin-ladder family material BiCu2VO6 is studied by means of the magnetic susceptibility, heat capacity and neutron inelastic scattering measurements on powder sample. Singlet ground state and a finite spin gap are confirmed by thermal-activated type susceptibility and by distinct peak at 16 meV in spin excitation. Triple narrow band structure in spin excitation spectrum, probably due to...
متن کاملElectron-spin dynamics in strongly correlated metals.
The temperature dependence of the electron-spin lifetime T1 and the g factor are anomalous in alkali fullerides (K,Rb)3C60, which cannot be explained by the canonical Elliott-Yafet theory. These materials are archetypes of strongly correlated and narrow band metals. We introduce the concept of a "complex electron-spin resonance frequency shift" to treat these measurables in a unified manner wit...
متن کاملSEMICONDUCTOR TO TRANSITION IN FeS
Summarised here are the conclusions of an investigation by differential thermal analysis, magnetic susceptibility, Mossbauer spectroscopy, electrical conductivity and thermoelectric power on single crystal Fe0.996S. There is an increase in conductivity both parallel and perpendicular to the c-axis by a factor 102 at Ta (420 K). At low temperature the I. S. is characteristic of a non-metal but i...
متن کاملDegenerate four waves mixing in multilayer nanoshell
We will present a detailed investigation of intersubband transitions process in core-multi shells quantum dots. The confined wave functions and eigenenergies of electrons in quantum dots have been calculated under the effective-mass approximation by solving a three-dimensional Schrodinger equation. Excellent dependence is found between size effects, time relaxation and degenerate four wave mixi...
متن کامل